Re: Understanding disassembly x86 + understanding function call + parameter pass and stack frame

2013-08-13 Thread nidhi mittal hada 
On Mon, Aug 12, 2013 at 8:37 PM, amit mehta gmate.a...@gmail.com wrote:

 On Mon, Aug 12, 2013 at 5:28 PM, nidhi mittal hada
 nidhimitta...@gmail.com wrote:
  Questions:-
  1)Which memory address in stack contains struct super_block *s
  2)how does disassembly helps in knowing which register contain the struct
  super_block *s
  3)bt -f gives highlighted above, register dump at the end, does that
 help in
  finding this information ???

 Have you *actually* spent your time on reading the AMD 64ABI [1] ?
 Also there is a very nice and concise document available on x86_64
 assembly [2]. While trying to analyse kernel crash dump using 'crash',
 utility you might want to refer this page [1] and this blog [4] as well.

 [1] http://www.uclibc.org/docs/psABI-x86_64.pdf
 [2] www.cs.cmu.edu/~fp/courses/15213-s07/misc/asm64-handout.pdf
 [3] http://people.redhat.com/~anderson/
 [4] http://www.sungju.org/?p=1166

 !!amit


*Thats my system on which  ran crash tool*
[nidhi@raw ~]$ uname -a
Linux raw.ind.hp.com 2.6.32-220.el6.hpsp16k1.x86_64 #1 SMP Mon Nov 19
17:07:07 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

*thats the information of coredump file:-*
  KERNEL: vmlinux
DUMPFILE: vmcore.1  [PARTIAL DUMP]
CPUS: 8
DATE: Mon Jun 11 09:10:59 2012
  UPTIME: 13 days, 22:39:30
LOAD AVERAGE: 83.88, 62.23, 30.30
   TASKS: 393
NODENAME: million.ind.hp.com
 RELEASE: 2.6.32-220.el6.hpsp16k1.x86_64
 VERSION: #1 SMP Mon Nov 19 17:07:07 UTC 2012
 MACHINE: x86_64  (2132 Mhz)
  MEMORY: 96 GB
   PANIC: Kernel panic - not syncing: Watchdog detected hard LOCKUP on
cpu 4
 PID: 26715
 COMMAND: mount.***
TASK: 8817dd4de0c0  [THREAD_INFO: 8802c3f8]
 CPU: 4
   STATE: TASK_UNINTERRUPTIBLE (PANIC)


Thank you very very much .. *It was so helpful what Tobias and amit
explained.*

I actually skipped AMD64 ABI considering its for AMD architecture and mine
was
x86_64 .. my mistake !!

i read from wikipedia x86 calling convention link.
What i read was that all function arguments should be on stack .. thats
where i was wrong!!!
I read that on x86_64 arg are pushed from right to left ..which also seems
wrong now..

Now i m finding AMD 64ABI is the thing to be read for understanding this
crash output.

Thanks a lottt

Nidhi
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Re: /proc/net/dev no such file or dir

2013-08-13 Thread Valdis . Kletnieks 
On Tue, 13 Aug 2013 21:43:55 +0800, Hatte John said:

 I  have not ever mount /sys and /proc filesystems, so is there other
 way to chech the host's ip address and netdevice information?

If in fact /sys and /proc aren't getting mounted, a *whole lot* of stuff
won't work (for instance, /bin/ps will break, as will /bin/df.  I'm reasonably
sure that most udev implementations need /sys around, so I'm surprised
that you're getting booted at all...


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